MortarThePoint

UFH antifreeze

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I have UFH pipes installed in screed and am unlikely to have any heat source available before the temperature starts to get low over winter. Do most people just have plain water in their UFH or is antifreeze usually added? Has anyone else gone through winter with UFH in place but unheated?

 

Another consideration is that once I eventually have the ASHP installed, I would like to be able to use it to cool the UFH during the summer. I'm sure it would be set up to keep the water above freezing, but a failure mode is to over call the water which could burst pipes.

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We had pipes in place throughout last winter, but kept them pressurised with air, not water. This means if anything gets damaged during first or second fix it's easy to see the pressure meter has dropped, but no damage done from leaked water.

 

ASHP won't cool water below freezing (ours only gets down to 5°C) so no risk of that damaging pipes. However anything below about 12-15° is liable to cause condensation which needs careful planning to manage / avoid

 

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1 minute ago, joth said:

We had pipes in place throughout last winter, but kept them pressurised with air, not water. This means if anything gets damaged during first or second fix it's easy to see the pressure meter has dropped, but no damage done from leaked water.

 

I have a compressor so could threoretically blow out the water, but I'd rather not I think.

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We had ours filled with water and pressurised last winter, just add antifreeze.  We used flowmaster antifreeze from Screwfix it's cheap and works.

 

When you install the piping, you need to do an initial stretch of the pipe wall at 10 bar, then lower the pressure and hold between 4 and 6 bar.

 

Filling with air has a lot of stored energy, so if anything does come loose you could damage equipment yourself or others.  You will have several hundred meters of of pipe with (maybe 10 bar) 4 to 6 bar in it. Equipment pressurised with air when it fails, fails with a huge amount of force, because the air is compressed and expands, water cannot be compressed, so when you get a failure it is a low energy event.  It's not safe I would recommend water and anti freeze, but it's your choice.

 

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On 28/10/2021 at 08:47, JohnMo said:

We had ours filled with water and pressurised last winter, just add antifreeze.  We used flowmaster antifreeze from Screwfix it's cheap and works.

 

Is there any trick as to how to add it to the system. I filled my UFH directly from mains so don't have a pump box. Might have to get a small water pump (like for fountains) as haven't plumbed up any proper water pumps yet (system is only UFH pipes and manifolds so far).

 

I presume this is what you used:

image.png.79b6675a9017b2f8703b6fda70458734.png

https://www.screwfix.com/p/flomasta-0623-concentrated-central-heating-inhibited-antifreeze-5ltr/4409r

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On 28/10/2021 at 08:47, JohnMo said:

you need to do an initial stretch of the pipe wall at 10 bar, then lower the pressure

 

Why do you need to stretch the piep wall at 10 bar?  Is this for a particular pipe or what.  Would like to understand the principle of this.

 

I know the risk of air test but again if you've pressure tested to a higher pressure and then dropped to 4 bar, if something still blows then its a poor instal.  We've pressure tested our systems with air for most of our 18 years in UFH.

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That's the anti freeze I used.

 

I had no water at site, so fill with a hand pump, same pump was used to pressure test.  So I pre mixed it with the fill water in the Jerry can.  To manually fill took about an hour (50 L)

 

RHays

10 bar is what the instructions of my pert-al-pert pipes stated.

 

The risk is at the high pressure, something is likely to fail at the high pressure, not when you have lowered the pressure.  Because you done something at lot of times doesn't mean it's safe or less unsafe.

 

 I've climbed ladders for 50 years, never had an issue, fell off one this week, it still hurts.

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I've used 16mm pipe with an ID=12mm so 113ml per metre. My total system volume is 180l, so I'd need 45l of this stuff or 9bottles at £202. Expensive but less than burst pipes.

 

Do most people have antifreeze/inhibitor in their UFH systems? I know inhibitor is a must for radiator systems, but don't know about UFH. @Nickfromwales do you normally install inhibitor antifreeze in UFH?

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Are the pipes empty and house up? I have my pipes in my insulated foundation, installed in April and have never had water or anything in them yet. House is up now and windows doors in, but no heating or anything else and I'm not planning putting anything in them. If there is no water why add it? 

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21 minutes ago, SuperJohnG said:

If there is no water why add it? 

Agreed, but still best to put under pressure at least when building, if not all the time.

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11 minutes ago, RHayes said:

Agreed, but still best to put under pressure at least when building, if not all the time.

Not really, what is the argument for doing so? So you know if a pipe gets punctured? If that happens mid build what are you going to do about it? Nothing.

 

If a pipe somehow gets punctured mid build you ain't doing nothing about it until you start bringing the heating online. It's sat in a concrete slab and in an 80m pipe could be anywhere. The only way to easily find is pump hot water through and use a flir to identify pooling.

 

So having the pipes under pressure doing the build is a pointless exercise. Even during a concrete pour, why? If one gets trodden on and punctures, like fook you're gonna stop the concrete pour to find it, you will crack on and park it as a future problem to deal with.

 

People on here seem to have an obsession with pressuring pipes. Pointless.

 

I would also suggest the pipes are very robust, to puncture one would be extremely unlucky.

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1 hour ago, SuperJohnG said:

Are the pipes empty and house up?

Pipes full of water and house roof on with proper windows half in (poly windows elsewhere).

 

 

36 minutes ago, LA3222 said:

Even during a concrete pour, why?

It is the conventional wisdom to do a wet pressure test before the pour and to leave it pressurised during the poor. The pressure test could identify if the pipe was damaged as laid or at another point prior to concrete which you could identify and rectify before pour. Agree you are unlikely to do anything during pour. But it's nice piece of mind to still have pressure after the pour. Finally, a pressurised pipe will better resist damage from being squashed. 6bar of pressure is around 100PSI so can resist the full weight of a person across an area of just 12mm x 100mm which is around a foot's width. Yes the pipe is strong, but may as well help it. Here I am convinced water is a better choice than air as air is compressible and water not. That means that air would only ever push back with the system pressure whereas water could momentarily increase the pressure, and locally due to inertia. The inertia of the water would resist impacts much better than air would.

 

36 minutes ago, LA3222 said:

People on here seem to have an obsession with pressuring pipes. Pointless.

 

I would also suggest the pipes are very robust, to puncture one would be extremely unlucky.

Agreed, but when inexperienced it is often about minimising unquantified risks. You don't have the experience to know it will be fine anyway so you do what you can to give yourself the best chance.

Edited by MortarThePoint

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18 minutes ago, MortarThePoint said:

It is the conventional wisdom to do a wet pressure test before the pour and to leave it pressurised during the poor.

This smacks of doing something because "thats what people do" rather than considering 'why' am I doing this and 'what does it achieve'.

 

20 minutes ago, MortarThePoint said:

The pressure test could identify if the pipe was damaged as laid or at another point prior to concrete which you could identify and rectify before pour.

The pipes come pre pressurised, the minute you cut it you will 'know' that the pipe hasn't been damaged during laying.

 

After laying its child play to walk around the slab without deliberately standing on the pipe.

 

During our you ain't doing anything about it. People will stand where they will.

 

22 minutes ago, MortarThePoint said:

Finally, a pressurised pipe will better resist damage from being squashed. 6bar of pressure is around 100PSI so can resist the full weight of a person across an area of just 12mm x 100mm which is around a foot's width. 

This is just a load of good old fashioned tosh! Yeah the maths works out, in practical terms it is over engineering at its finest. The pipe is solid, I could jump up and down all day long on a piece sat on mesh and the odds of me piercing it are low.

 

If you want to do it then do it, it doesn't cost anything other than a few quid and some time.

 

I would question what is the point.

 

I did all of my slab except the concrete pour, was walking all over the pipe for weeks before concrete went in, didn't waste my time pressurising and no drama.

 

That pipe is solid, you ain't gonna puncture it unless trying to. The thing to worry about is kinking it rather than puncturing it. 

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1 hour ago, LA3222 said:

This smacks of doing something because "thats what people do" rather than considering 'why' am I doing this and 'what does it achieve'.

 

The pipes come pre pressurised, the minute you cut it you will 'know' that the pipe hasn't been damaged during laying.

 

After laying its child play to walk around the slab without deliberately standing on the pipe.

 

During our you ain't doing anything about it. People will stand where they will.

 

This is just a load of good old fashioned tosh! Yeah the maths works out, in practical terms it is over engineering at its finest. The pipe is solid, I could jump up and down all day long on a piece sat on mesh and the odds of me piercing it are low.

 

If you want to do it then do it, it doesn't cost anything other than a few quid and some time.

 

I would question what is the point.

 

I did all of my slab except the concrete pour, was walking all over the pipe for weeks before concrete went in, didn't waste my time pressurising and no drama.

 

That pipe is solid, you ain't gonna puncture it unless trying to. The thing to worry about is kinking it rather than puncturing it. 

 

Fair play, you now have the experience to know how robust it is. Personally, I still wouldn't risk it and would pressure test and then leave the water in. It's less buoyant with water in, but shouldn't be going anywhere anyway. I think I read somewhere about the initial deformation of the pipes when pressurised, but it's not like screed isn't strong enough to resist that.

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Agreed, pipes are robust but you'd be supprised what happens.  The principle behind pressurising it (whether air or water) during the build is that you will be able to tell where it comes from as soon as it is puncture, either by escaping air or a pool of water.  That way doing further testing down the line which isn't always as easy as hot water and flir isn't needed, even if you do deal with it at a later date.  Anyway, why not leave it under pressure.  Nothing to loose as far as I can tell.

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On 30/10/2021 at 08:55, MortarThePoint said:

Do most people have antifreeze/inhibitor in their UFH systems? I know inhibitor is a must for radiator systems, but don't know about UFH. @Nickfromwales do you normally install inhibitor antifreeze in UFH?

Only with an ASHP install. 

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I needed anti freeze in my gas powered UFH as it pressurised during last winter without the house to keep it frost free.  The slab was a huge chunk of ice most of last winter.  So well insulated, that once it froze it stayed frozen for days.

 

But this has mostly been flushed out now get air out the system during commissioning.

IMG_20201117_100526.jpg

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I used my compressor to flush the system yesterday. Sprayed the walls a few times, but think I got most of the water out. Left at 3bar air pressure.

 

It's obvious to see how much more effective water is at leak detection through pressure loss than air is due to air compressibility

Edited by MortarThePoint

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Use soapy water at the joints, if foams you have a leak, if it doesn't you don't

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